APA
van Opstal M., . (1999). Social security law : Suppl. 27 Case Law (7). The Hague, London, Boston: Klumer Law international P.O. Box 322 3300 AH Dordrecht.
Chicago
van Opstal M, . 1999. Social security law : Suppl. 27 Case Law (7). The Hague, London, Boston: Klumer Law international P.O. Box 322 3300 AH Dordrecht.
Harvard
van Opstal M., . (1999). Social security law : Suppl. 27 Case Law (7). The Hague, London, Boston: Klumer Law international P.O. Box 322 3300 AH Dordrecht.
MLA
van Opstal M, . Social security law : Suppl. 27 Case Law (7). The Hague, London, Boston: Klumer Law international P.O. Box 322 3300 AH Dordrecht. 1999.